[NoobOnTour]

Hey guys
once again iam in need of your advice

I want to use extension tubes but since my DA50 is lacking an aparture ring a "new" prime is needed.
(extension tube aside, a new lens is always nice )

would you go for an manual 50/100/135 lens?
Is there a focal length / Prime you can recommend?
Any other suggestions are welcome, too!

I thought about one of these:
M 50mm F1.4
M 100mm F2.8
M 135mm F3.5

or go straight for a macro lens?

greetings Sascha

[robthebloke]

There are extension tubes available with the 'A' contacts, those would work with your DA50. There also autofocus tubes available (but I'd avoid them unless your lens has quick shift, which the DA50 lacks).

50mm is the best bet for tubes. Add a 50mm extension, and you get 1:1 equivalent. Any 50mm f1.7 or similar would do the job.

---------- Post added 01-10-16 at 01:26 PM ----------

But yeah, I'd say go straight for a macro lens. The DA35 f2.8 is superb, slightly lower cost would be any of the 50mm f2.8 Pentax lens. You may be able to find a cheap(ish) sigma lens second hand (eg 50mm, 70mm, or 105mm)

[sergysergy]

I have always used my M 50 1.7 with great results.

[MPrince]

I have an A 50 f/2.0 I'd be willing to part with if you're interested.

[Scorpio71GR]

Any lens with an apeture ring will work. I have extension tubes but rarely ever use them for macro. I just do not seem to have the patience I guess. I prefer to use a regular macro lens. The M501.7 would be a nice inexpensive choice. There is no need for lens with an A setting since the extension tubes do not transmit information. Unless you have the Kenko extension tubes with the contacts. They rarely come up for sale and usually sell for around $150 or more. I have the FA 50 macro and that is one extremely sharp lens.

[marcusBMG]

You can use tubes and expect good results with any quality prime. All the fifties will do well.

As robthebloke says the pka extension tubes are the ones to get to use with the aperture ring-less DA50 because then the aperture is set on the camera, only trouble is they are hard to find.
Jessops Auto Extension Tubes PK-A reviews - Pentax Camera Accessory Review Database

I did a quick browse ebay europe wide and the only seller I could find was in London for an extortionate £129. For that price you might as well simply splash on a dedicated macro lens; the adaptall 52B 90mm, with a PKA mount, should cost about that, or less if you are a sharp ebayer.
Plenty of PKM tubes available, without contacts, in fact I have a set listed for sale here, which would work fine in M mode with any of the classic K, M. A etc primes.

A shorter focal length gets bigger magnification more quickly. With eg a 28mm or 35mm you could try using a deglassed pka mount teleconverter, you can pick up one of those cheaply relatively easily. They are usually around 3cm extension, enough to get to ~ 1:2 with a fifty. Working distances ie from the end of your lens, get very small very quickly with the shorter focal lengths though.

There are other options - check out this general account. I have a panagor macro converter myself, just taken a few initial test pics so far with my smc-a 50mm 1.7, looks sharp.

PANAGOR AUTO MACRO CONVERTER reviews - Pentax Camera Accessory Review Database

And the raynox's are well regarded and very effective
Raynox DCR-150 reviews - Pentax Camera Accessory Review Database

[TaoMaas]

Extension tubes are nice because they can add close-up ability to almost any lens and that can greatly expand the capabilities of your kit. However, they're nowhere near as convenient as a dedicated macro lens. I don't know what your budget is, but it's possible to find used 50mm or 100mm macro lenses for around $100 or less. The nice thing is that macro lenses are a lot like 50mm lenses in that even the less desirable ones are pretty darned good. I bought an older Pentax 50mm f4 macro off Ebay this past year for right around $50.

[pathdoc]

These extension tube systems are optimised for use with 50mm or 55mm K and M type lenses, and are best used with a lens that has an aperture ring - that way if you can't find a set with automatic contacts you can still stop it down. K, M and even A 50mm lenses should not be that expensive. The dedicated macros will give the best results and maximum magnification, of course, but part of the charm of extension tubes is the ability to do some form of macrophotography with standard lenses.

If you need flexibility, of course, you will need either a macro tube with continuous (helicoid) focusing or a bellows unit.

[Not a Number]

Any of the manual focus 50mm f1.7 are good choices. Good value for the price, tend to have better flat-field performance than the f1.4 or f1.2. Indeed the Pentax bellows manuals recommend using the f1.7s over the f1.4 and not using the f1.2 at all for macro. Of course the subject matter makes a difference too - flat field performance may not be a concern with more "3D' objects.

"A" version would still be a good value as you can use the "A" function without the tubes as a prime lens. The aperture ring spring flaw would be a drawback but can be repaired DIY.

Any of the manual focus 50mm macros are only going to give 0.5x magnification so you'll need an extension tube if you want more magnification. Or you could use close-up lenses instead of tubes.

[UncleVanya]

A reversed 28ish lens is another option. An m42 extension set ( if you already have the adapter ) plus an enlarging lens can be another inexpensive approach.

[NoobOnTour]

thanks guys!
i see there is a lot to check up.

Iam not quite sure if i understand the "flat-field performance" issue correctly.
So there is a difference even if I use a smaller aperture?

[blende8]

Flat field means that if you focus exactly on the center, the corners are equally sharp.
Often the fast lenses (1.4 and higher) suffer from field curvature, resulting in soft corners.
So, if you are into photographing postal stamps, this may be an issue.

Indeed the Pentax bellows manuals recommend using the f1.7s over the f1.4 and not using the f1.2 at all for macro.

I have also read that lenses that are symmetrically built, like the 50/1.7, are better for macro.

[pathdoc]

Basically flat field performance only matters for such things as document copying, itself a relic of the days before scanners and photocopiers. When you are taking a picture of something like the front page of a newspaper or a page of a book, the edges of the subject are ever so slightly further away from the centre of the front element than the centre of the field of view, and that can create blurring or distortion issues such that the reproduction is not a faithful one.

Macro lenses (especially the older ones, which were optimised for this) tend to have their optics set up to counteract those problems, so you pay a premium. That being said, if you are emphasising (for example) a spider's multiple googly eyes and lethal jaws right in the middle of the field of view, a little bit of distortion out towards the edge of the picture where the legs are is not going to be an issue. OTOH if you are photographing the Magna Carta or the US Declaration of Independence for the last time, minutes before the repository is destroyed by aliens, it might matter a whole lot.

[UncleVanya]

Basically flat field performance only matters for such things as document copying, itself a relic of the days before scanners and photocopiers. When you are taking a picture of something like the front page of a newspaper or a page of a book, the edges of the subject are ever so slightly further away from the centre of the front element than the centre of the field of view, and that can create blurring or distortion issues such that the reproduction is not a faithful one.

Macro lenses (especially the older ones, which were optimised for this) tend to have their optics set up to counteract those problems, so you pay a premium. That being said, if you are emphasising (for example) a spider's multiple googly eyes and lethal jaws right in the middle of the field of view, a little bit of distortion out towards the edge of the picture where the legs are is not going to be an issue. OTOH if you are photographing the Magna Carta or the US Declaration of Independence for the last time, minutes before the repository is destroyed by aliens, it might matter a whole lot.

Those aliens again? We need a good exterminator.

[NoobOnTour]

thank you for clarifying this